package com.hmdp.service.impl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;

import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;

import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;


import javax.annotation.PostConstruct;
import javax.annotation.Resource;

import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;


@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {


    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    //lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    //存储订单的阻塞队列，参数为队列长度
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    //执行任务的线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    //当前类初始化完毕就执行该方法
    @PostConstruct
    public void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    //任务
    private class VoucherOrderHandler implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (InterruptedException e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }
    //完成库存扣减和订单生成
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1. 获取用户对象
        Long userId = voucherOrder.getUserId();
        //2. 创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = lock.tryLock();
        if (!isLock) {
            //获取锁失败，返回失败或者重试
            log.error("不允许重复下单");
            return;
        }
        try {
            proxy.createVoucherOrder(voucherOrder);
        }finally {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;

    /**
     * 秒杀优惠券
     * @param voucherId 优惠券id
     * @return 订单id
     */
    @Override
    public Result seckillVoucher(Long voucherId) {

        Long userId = UserHolder.getUser().getId();
        //1. 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        int r = result.intValue();
        if(r != 0){
           return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
       }
       //2.保存消息到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //用户id
        voucherOrder.setUserId(userId);
        //代金券id
        voucherOrder.setVoucherId(voucherId);
        //放入阻塞队列
        orderTasks.add(voucherOrder);
        //获取代理对象 事务
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //3.返回订单id
        return Result.ok(orderId);
    }


    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //一人一单逻辑
        Long userId = voucherOrder.getUserId();
        //查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count().intValue();
        //判断是否存在
        if (count > 0) {
            //用户已经购买过了
            log.error("用户已经购买过一次！");
            return;
        }
        //扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
                if (!success) {
                    //扣减失败
                    log.error("库存不足！");
                    return;
                }
                save(voucherOrder);
    }
}
